Unless otherwise indicated herein, the materials described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section.
A cellular wireless network may include a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or a packet-switched network such as the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs.
In an example arrangement, the network infrastructure may include one or more packet-data network gateways (PGWs) or similar components that provide connectivity with a packet-switched network so as to support various communication services, such as general Internet communications, voice-over-IP communications, and the like.
In practice, when a UE enters into coverage of a base station, the UE may engage in a process or registering or “attaching” with the network, which may trigger setup of a bearer (logical communication tunnel) extending between the UE and a PGW, so that the PGW can then serve the UE with packet-data communications. For instance, upon detecting coverage of the base station, the UE may transmit to the base station an attach request, which the base station may then forward to a controller such as a mobility management entity (MME). After authenticating the UE, the MME may then engage in bearer-setup signaling with the base station and with a serving gateway (SGW), the base station may establish a radio link layer connection for the UE, the SGW may engage in bearer-setup signaling with a PGW, and the PGW may assign an IP address for use by the UE to engage in packet-data communications.
In essence through this process, the network may thus establish specifically for the UE what may be considered a “unicast bearer,” including a radio bearer segment between the UE and the base station and an access bearer segment extending between the base station and the PGW. When the UE has data to transmit on the packet-switched network, the UE may then transmit the data on that unicast bearer to the PGW, with the data flowing from the UE to the base station on air interface resources assigned specifically to the UE, and then from the base station to the SGW and from the SGW to the PGW, for transmission from the PGW onto the packet-switched network. Likewise, when the PGW has data to transmit to the UE, the PGW may transmit the data on the unicast bearer to the UE, with the data flowing from the PGW to the SGW, from the SGW to the base station, and from the base station to the UE on air interface resources assigned specifically to the UE.
In addition to supporting unicast communication with particular UEs, the network may also support broadcast communications to UEs. To facilitate this in example arrangement, the network may include a broadcast server that receives media content from a content provider and transmits the content over a broadcast bearer established generally between the server and one or more base stations, and as each base station receives the content, the base station may broadcast the content on air interface resources reserved for the broadcast session. To set up such a broadcast, the base station may first broadcast a control channel message that informs UEs about the session, providing information such as what air interface resources will carry session content and when the session will start. Each UE that desires to receive the broadcast may then transmit a join-request to the base station, which may pass through the network to the broadcast server, and the broadcast server may then respond to each such join-request by providing the UE with information such as packet ID numbers, keys, or the like, that will enable the UE to receive and play out the session content. At a designated start time, the broadcast server may then begin transmitting the media content over the broadcast bearer to each participating base station, and the base station may broadcast the content for receipt and playout by any and all participating UEs.
Such a network may be arranged to have multiple base stations in a region concurrently provide such a broadcast, so that UEs receiving the broadcast can move between coverage of the base stations and continue to receive and play out the broadcast session content. To facilitate this, the broadcast server may transmit the media content to a multicast gateway, and the multicast gateway may multicast the content to the participating base stations, effectively defining a broadcast bearer extending from the broadcast server to the participating base stations. Further, a multicast coordinating entity may work with the base stations to help ensure that they broadcast the media content at the same time as each other, so that UEs can move between base station coverage areas and seamlessly continue to receive the broadcast content.